Question

what I need (and got with temporary tables or views is this):

numcasos  valcount1  valcount2  
--------  ---------  -----------
       0          2            1
       1          1            2
       2     (NULL)       (NULL)
       3     (NULL)            1
       4          1       (NULL)
       5     (NULL)       (NULL)
       6     (NULL)       (NULL)
       7     (NULL)       (NULL)
       8     (NULL)       (NULL)
       9     (NULL)       (NULL)
      10     (NULL)       (NULL)

This is an example because I need it for 300+ valcounts. MySQL:

CREATE TEMPORARY TABLE sumnum1
SELECT numos.num1 AS num1,
 COUNT(*)   AS valcount1      
FROM `numos` 
GROUP BY numos.num1  ; 

CREATE TEMPORARY TABLE sumnum2
SELECT numos.num2 AS num2,
 COUNT(*)   AS valcount2      
FROM `numos` 
GROUP BY numos.num2  ; 



SELECT casos.`numcasos` AS numcasos, 
sumnum1.valcount1 AS valcount1,
sumnum2.valcount2 AS valcount2

FROM ( casos
LEFT JOIN sumnum1
ON (casos.`numcasos`= sumnum1.num1)
LEFT JOIN sumnum2
ON (casos.numcasos = sumnum2.num2))

what I would like is to get the same result with subqueries instead but I get the error message:

Subquery returns more than 1 row

Is it possible in MySQL?

Answer 1

Try something like

SELECT casos.numcasos AS numcasos, 
sumnum1.valcount1 AS valcount1,
sumnum2.valcount2 AS valcount2
FROM casos
LEFT JOIN
(
    SELECT numos.num1 AS num1, COUNT(*) AS valcount1
    FROM numos GROUP BY numos.num1 
)sumnum1  ON (casos.`numcasos`= sumnum1.num1)
LEFT JOIN 
(
   SELECT numos.num2 AS num2, COUNT(*) AS valcount2
   FROM numos GROUP BY numos.num2  
)sumnum2 ON (casos.numcasos = sumnum2.num2))